Question

The ionization energy decreases from nitrogen to oxygen, why?

The ionization energy decreases from nitrogen and oxygen and I was told it is because it is taken from a doubly occupied `p` orbital, then why doesn't the ionization energy decrease from boron to carbon, doesn't carbon have a doubly occupied `p` orbital as well?

Answer 1

Nitrogen is more stable than Oxygen so it would take more energy to make it an ion.

Explanation:

Stability is related to ionization energy. If an atom is more stable, it takes more energy to remove an electron so it's ionization energy is higher.
Nitrogen has 3 electrons in it's highest energy level, which can hold 6, so that's half-filled, and that has some stability.
Oxygen has 4 electrons in that same energy level, and that does not give it stability since it is over half-filled.
Having a half-filled electron orbital gives Nitrogen more stability than Oxygen so it would take more energy to remove it's most loosely held electron, which is how the ion forms.